Hey guys...I'm swapping out my stock HU for an Aquatics unit and swapping out my PA RZ4-2000D for a JL MHX 280/4 (bridging to my BT 7.1's...for now anyway).

I have some install questions:

• Do I need an amp tray to mount the amp? (I currently have my PA velcro'd to the top of the stock HU, and I found it tough to fit.)
• How do you adjust the amp with the controls on the bottom?
• With the Aquatic do I need line levelers or just RCA's?
• Can I use my current power/ground wiring?
• Anything I'm missing?

Thanks in advance,
Mark

 

Before mounting the amp on the HU, before you hook up your speakers, download yourself a 1000-Hz Sine Tone, start the bike, set your radio to 3/4 max volume and use a DMM to set the amp gains at your target wattage which with that amp bridged and the 7.1s wanting 125W RMS, the VAC should be between 22 and 22.4 Once both channels are set, remove the sine tone. do not play it through your speakers! Your amp is set, screw in the bottom plate and mount it up. The directions on how to bridge that amp are pretty straightforward and what settings on the amp and what RCAs to plug into, etc.

Whether or not you can use your current ground and power depends on what your current setup looks like. I'm sure if your PA ran fine, the JL will run fine too.

The aquatic has RCA pre outs, no line leveler needed but you will probably want to pick up two male to male RCA barrel connectors...the pigtail off the JL amp is pretty long so it ought to reach the Aquatic outputs.

If setting amp gains with a DMM is foreign to you, there's a sticky at the top of this section that walks you through step by step.

 

Cp is pretty much dead on with his recommendation.

Couple things I would add.

1. Set your HP crossovers to 80hz and turn your gain ***** all the way down before you begin.

2. Make sure your HU is set to flat or 0db EQ before you begin. After the target voltage is reached you can go back in and set your EQ.

3. Make sure your DMM is set to AC.

4. Also keep in mind that amp does better than rated on the dyno. The specs show 140 watts bridged but you're actually looking at about 185 watts. This will change your target voltage.

 

Thanks guys! Sorry...new to setting with a DMM. So if I understand correctly, does that mean that since the dyno shows 185 that the 22 on the DMM may actually be higher output than if calculated on the specs? Can I compensate by percentage, or how would I make that adjustment?

Thanks!

 

U will determine the ac voltage based on the speaker RMS and also what the amp is comfortably rated at. The is a free app called Ohms Law that lets u enter the appropriate values and it will spit out the vAC u will set to obtain a certain amp Watt output.

For long term reliability I would not run the 280/4 much higher than about 24.5 to 25 as higher is putting it real close to the edge of its sandbox. I ran one hard at the dynamic value on a 2 day road trip and it fried itself. Too much vAC and a big draw speaker simply overworked it.

T.

 

The simplest way is to use Slye's chart in the sticky at the top of the forum. 185 watts @ 4 ohms you're looking at between 24.5 and 28.3 vac. I would split the difference and use roughly 26.4 vac for my target voltage. Always use your ears as well. This gain setting thing can be very subjective unless you're using an oscilloscope. But the DMM will get you dam close. The main thing you don't want is distortion. If it distorts at anytime during the process. back off a hair. Otherwise you're GTG!

 

so...initial setting by DMM then tweak settings by ear. Got it.

 

The reason I set him at 22 is because the BT speakers only want 120 watts if they can handle more, then by all means head up to 24 but I figured better safe than sorry. The amp is definitely capable of more.

 

heard and appreciated.

 

i purchased the base model aquatic last year and there was no RCA pre-outs for the front channels, only the rears, but also included high level outs for the rears. did i miss something?